I recently created an Excel macro that creates AutoCorrect entries for all ˣ⁄₂, ˣ⁄₄, ˣ⁄₈, ˣ⁄₁₆, ˣ⁄₃₂ and ˣ⁄₆₄ fractions from ¹⁄₆₄ to ⁶³⁄₆₄. Once created in Excel, they will be available to all Office programs.
You can find a copy of the sample workbook with that macro, the helper UDF and an automated removal macro from my SkyDrive here:
Edit: added image